Facial Nerve Outcomes Following Total Excision of Vestibular Schwannoma by the Enlarged Translabyrinthine Approach

A rare case of vestibular schwannoma manifesting as trigeminal neuralgia

BACKGROUND

In this case report, the authors reviewed a rare case of a vestibular schwannoma manifesting as trigeminal neuralgia (TN). Intracranial tumors can have a variety of orofacial pain symptoms. Among benign cerebellopontine angle tumors, vestibular schwannoma is the most common cause of a TN-like manifestation. Although the most common symptoms of a vestibular schwannoma are hearing loss and vestibulopathy, the unique feature of this case was the manifestation of symptoms consistent with TN.

CASE DESCRIPTION

The patient had right-sided episodic facial pain that was short in duration and severe in intensity. The initial differential diagnoses included short-lasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing and TN. As part of the routine evaluation, the patient was referred for brain magnetic resonance imaging, which revealed a right-sided vestibular schwannoma. The patient was prescribed 200 mg of gabapentin 3 times daily and was referred to neurosurgery for excision of the schwannoma. Surgical excision resulted in complete resolution of pain.

PRACTICAL IMPLICATIONS

This case illustrates the importance of interdisciplinary treatment and how it can lead to an optimal outcome for a patient with complex orofacial pain symptoms.

Management of Vestibular Schwannoma with Normal Hearing

INTRODUCTION

This work aimed to study the management of vestibular schwannoma (VS) patients with normal hearing (NH).

METHODS

A retrospective study was undertaken in a Quaternary referral center for skull base pathologies. Among 4,000 VS patients 162 met our strict audiological criteria for NH. These patients were divided into 2 management groups, wait and scan (W&S) (45/162, 25%) and operated patients (123/162, 75%), and 6 patients were included in both groups.

RESULTS

Our management strategy achieved the goals for treatment of VS. First goal, all tumors were completely removed except for 2 intentional residuals. Second goal, facial nerve (FN) function preservation (House Brackmann I, II, and III) was 95.9%. Third goal, possible hearing preservation (HP) attempts occurred in (50/122) (40.9%) with an HP rate in 44% of the patients. Additionally, there were only 2 cases of postoperative complications with no CSF leakage. The prospect of HP in NH patients did not differ with respect to tumor size. However, patients with normal preoperative ABR seemed to have better chances of HP and good FN function and vice versa. HP rate was superior for the MCFA as opposed to the RS + RLA. W&S group demonstrated hearing stability in 88.9% of the patients and FN function stability of HB I in 100% of the patients.

CONCLUSIONS

Surgical resection is a reasonable and definitive management option for VS with NH. Nevertheless, choosing to manage cases with observation remains an appropriate management option for NH patients. ABR might be considered as an adjuvant tool indicating better prognosis for HP.

Early Translabyrinthine Surgery for Small- and Medium-Sized Vestibular Schwannomas: Consecutive Cohort Analysis of Outcomes

OBJECTIVE

Reappraisal of the role of translabyrinthine (TLAB) surgery in small- and medium-sized vestibular schwannomas (VSs).

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

A total of 330 consecutive patients diagnosed between 1973 and 2019 with small- and medium-sized VS up to 20 mm in the extrameatal portion submitted to surgical treatment.

INTERVENTIONS

VS removal through microscopic TLAB approach.

MAIN OUTCOME MEASURES

Facial nerve function according to the House-Brackmann scale at 12-month follow-up, postoperative complications and entity of tumor resection assessed with postoperative MRI. A comparative analysis of outcomes between two groups of patients was further conducted, according to tumor size: Group A, small-sized (intrameatal or ≤10 mm extrameatal tumors) and Group B, medium-sized VSs (extrameatal between 11 and 20 mm).

RESULTS

Complete tumor removal was achieved in all cases. The overall complication rate was 5.5%, being cerebrospinal fluid leak the most frequent. Patients with small-sized VS (n = 121) presented a significantly better facial nerve function than patients with medium-sized tumors (n = 209), showing House-Brackmann Grades I to II in 92.6% versus 73.6% of cases, respectively ( p < 0.001). A nearly 4.5-fold higher risk of poor facial nerve function at 12 months affects patients with medium-sized tumors (odds ratio, 4.473; 95% confidence interval, 2.122-9.430; p < 0.001).

CONCLUSION

In the current scenario of multioptional VS management, when hearing preservation is not feasible, early TLAB approach as first-line treatment for small-sized VSs showed favorable results. Factors supporting such proactive surgical treatment include long-term definitive cure, no major complications, good facial nerve outcomes, and the possibility of simultaneous hearing rehabilitation with a cochlear implant.

Neuro-Ophthalmic Complications of Vestibular Schwannoma Resection: Current Perspectives

Vestibular schwannomas (VSs), also called acoustic neuromas, are benign intracranial neoplasms of the vestibulocochlear (VIII) cranial nerve. Management options include “wait-and-scan,” stereotactic radiosurgery and surgical resection. Due to the proximity of the VIII nerve to the facial (VII) nerve in the cerebello-pontine angle, the VII nerve is particularly vulnerable to the effects of surgical resection. This can result in poor eye closure, lagophthalmos and resultant corneal exposure post VS resection. Additionally, compression from the tumor or resection can cause trigeminal (V) nerve damage and a desensate cornea. The combination of an exposed and desensate cornea puts the eye at risk of serious ocular complications including persistent epithelial defects, corneal ulceration, corneal vascularization, corneal melting and potential perforation. The abducens (VI) nerve can be affected by a large intracranial VS causing raised intracranial pressure (a false localizing sign) or as a result of damage to the VI nerve at the time of resection. Other types of neurogenic strabismus are rare and typically transient. Contralaterally beating nystagmus as a consequence of vestibular dysfunction is common post-operatively. This generally settles to pre-operative levels as central compensation occurs. Ipsilaterally beating nystagmus post-operatively should prompt investigation for post-operative cerebrovascular complications. Papilledema (and subsequent optic atrophy) can occur as a result of a large VS causing raised intracranial pressure. Where papilledema follows surgical resection of a VS, it can indicate that cerebral venous sinus thrombosis has occurred. Poor visual function following VS resection can result as a combination of all these potential complications and is more likely with larger tumors.

Impact of extent of internal acoustic meatus tumor removal using translabyrinthine approach for acoustic neuroma surgery

Objectives

Many studies have investigated the surgical outcome and predictive factors of acoustic neuroma using different approaches. The present study focused on large tumors due to the greater likelihood of internal acoustic meatus involvement and the greater application of surgical intervention than radiosurgery. There have been no previous reports on outcomes of internal acoustic meatus tumor removal. We investigated the impact of the extent of internal acoustic meatus tumor removal using a translabyrinthine approach for large acoustic neuroma surgery and predictive factors of tumor control.

Methods

This retrospective study reviewed 104 patients with large cerebellopontine angle tumor >3 cm treated by translabyrinthine approach microsurgery. Predictive factors of postoperative facial palsy, tumor control, and extent of internal acoustic meatus tumor removal were assessed.

Results

The mean tumor size was 38.95 ± 6.83 mm. Postoperative facial function showed 76.9% acceptable function (House–Brackmann grade 1 or 2) six months after surgery. The extent of internal acoustic meatus tumor removal was a statistically significant predictor factor of poor postoperative facial function. Younger age, larger tumor size needing radiosurgery, and more extensive removal of tumor were associated with better tumor control.

Conclusion

More extensive internal acoustic meatus tumor removal was associated with poor postoperative facial function and better tumor control.

Intracanalicular Vestibular Schwannoma: A Systematic Review and Meta-analysis of Therapeutics Outcomes

OBJECTIVE

To perform a systematic review and meta-analysis summarizing the current evidence on the management of intracanalicular vestibular schwannoma.

DATA SOURCES

Embase (1947-), Medline (1946-), Cochrane library (1947-), Scopus (2010-), and CINAHL (1961-) were searched from 1969 to October 5, 2019 (50 years).

STUDY SELECTION

A search strategy was performed to identify patients with vestibular schwannoma confined to the internal auditory canal without extension to the cerebellopontine angle. Studies with patients aged less than 18, Neurofibromatosis type 2, revision cases, and non-English language were excluded.

DATA EXTRACTION

A standardized collection sheet was used for the extracted data and a quality assessment was performed using the Newcastle-Ottawa Scale with the comparability criterion omitted.

DATA SYNTHESIS

Seventy-one studies were included with 24 on observation, 14 on radiotherapy, and 34 on surgery. The primary outcome was serviceable hearing preservation. Secondary outcomes were preservation of facial nerve function, growth, involution, and dizziness. Sub-analysis on the type of surgery and type of radiotherapy were performed. Excel 2016 with MIX 2.0 Pro add-on package was used to analyze the data and create forest plots. Data were presented in proportion with a 95% confidence interval.

CONCLUSIONS

Serviceable hearing was observed in 31% of patients after observation, 56% after radiotherapy, and 51% after surgical treatment with mean follow-up time of 4.04 years, 4.92 years, and 2.23 years, respectively. Facial nerve function was found to be best preserved in both observation and radiotherapy groups. Vestibular schwannoma growth occurred in 33% of patients under observation. Involution occurred in 2% of patients under observation and in 38% after radiotherapy.

The Association of Vestibular Schwannoma Volume With Facial Nerve Outcomes After Surgical Resection

OBJECTIVE

To explore the relationship between tumor size and facial nerve outcomes following vestibular schwannoma (VS) resection.

STUDY DESIGN

Single institutional retrospective chart review of all adult patients with untreated sporadic VS who underwent surgical resection from 2008 to 2018 with preoperative magnetic resonance imaging (MRI) and 1 year of follow-up. The primary outcome measure was facial nerve outcome as assessed by the House-Brackmann facial nerve grading system.

RESULTS

One hundred sixty-seven patients, 54.5% female, with a median age of 49 years (20-76 years), were identified who underwent VS resection. Surgical resection was performed by translabyrinthine (76.7%), middle cranial fossa (14.4%), retrosigmoid (7.2%), and transpromontorial (1.8%) approaches. The median tumor diameter and volume were 25.3 mm (range: 4.1-47.1 mm) and 3.17 cm³ (range: 0.01-30.6 cm³ ), respectively. The median follow-up was 24.2 months (range: 12-114.2 months). Gross total resection was performed in 79% of cases, with residual tumor identified on MRI in 17% of cases. For patients with tumors <3 cm³ , 92.7% had grade 1 or 2 facial function after at least 1 year follow-up, compared to 81.2% for those with tumors >3 cm³ (univariate logistic regression OR = 2.9, P = .03). Tumor volume >3 cm³ was predictive of facial weakness on multivariate regression analysis (OR = 7.4, P = .02) when controlling for surgical approach, internal auditory canal extension, anterior extension, age, gender, and extent of resection.

CONCLUSIONS

Tumor volume >3 cm³ is associated with worse facial nerve outcomes 12 months following surgical resection.

LEVEL OF EVIDENCE

IV Laryngoscope, 131:E1328-E1334, 2021.

"Large and giant vestibular schwannomas: overall outcomes and the factors influencing facial nerve function"

(1) To study the overall outcomes of patients surgically treated for large/giant vestibular schwannomas (VSs) and (2) to identify and analyze preoperative and intraoperative prognostic factors influencing facial nerve (FN) outcome. A retrospective clinical study was conducted at a quaternary referral otology and skull-base center. A total of 389 cases were enrolled. The inclusion criteria were patients with tumor > 30 mm undergoing surgery with a minimum follow-up of 12 months. Neurofibromatosis-II, previous radiotherapy, revision surgeries, preoperative FN House-Brackmann (HB) grade > I, partial resections, incomplete records, or those lost to follow-up for a minimum period of 1 year were excluded. In addition, partial resections and cases where FN was sacrificed intraoperatively were also excluded and were analyzed separately. The mean duration of symptoms was 35.4 months, pronounced more in elderly (58.3 months) than in younger individuals (28.4 months). Mean tumor diameter was 36 mm and 52.7% was cystic. Total resection (TR), near total resection (NTR), and subtotal resections (STR) were achieved in 77.4%, 9.5%, and 13.2% of cases, respectively. Regrowth was observed only after STR (19.6%). Good (HB I-II), moderate (HB III), and poor (HB IV-VI) FN functions were observed in 36.8%, 51.7%, and 11.6% cases, respectively. Younger individuals underwent TR in 259 (86.9%) cases against 42 (46.2%) in elderly individuals. Non-total resections (NTR/STR) were performed in 49 (53.8%) cases in elderly as against 39(13.1%) in younger individuals. Good FN outcome was observed in 28 (57.1%) cases of non-total resections in elderly as against 13 (33.3%) cases in younger individuals. On multiple logistic regression analysis, size of the tumor, preoperatively prolonged duration of symptoms, profound deafness, and antero-superiorly located FN with respect to the tumor played a detrimental role in the final facial nerve outcome postoperatively. On the contrary, in large tumors (3-3.9 cm), presence of vertigo/disequilibrium had a relatively better impact on final FN outcome. Partial resections accounted for 41(7.8%) cases and FN was interrupted in 71(13.6%) cases in total. Factors detrimental to better FN outcome were giant VSs (> 4 cm), antero-superiorly located FN intratumorally, preoperatively prolonged duration of symptoms, and profound deafness. In large tumors (3-3.9 cm), presence of vertigo/disequilibrium had a better impact on FN outcome. Understandably, cases with TR in comparison with NTR/STR had worse FN outcomes. In comparison with younger patients, elderly patients underwent higher NTR/STR resulting in better FN outcomes. The above factors can be used as prognosticators for patient counseling and surgical decision making.

Meningiomas of the Internal Auditory Canal

OBJECTIVE

Identify and define specific preoperative and postoperative characteristics of intracanalicular meningiomas (ICMs) in order to improve their diagnosis and management, and to differentiate them from intrameatal vestibular schwannomas (IMVSs).

METHODS

Preoperative symptomatology, magnetic resonance imaging (MRI), and postoperative outcomes of 28 ICMs were analyzed. The results were compared to the literature and IMVSs treated by our group.

RESULTS

Anacusis and progressive hearing loss were more frequent in the present population than the cases reviewed (P = .0064 and P = .0001, respectively). Hearing loss affected more than 90% of the patients, with anacusis in 32.1% of the cases. Facial palsy affected 17.9% of the patients. In comparison to IMVSs, preoperative anacusis was more associated to meningiomas (P = .0037), and the facial nerve was more compromised in ICMs than IMVSs, both preoperatively (P = .0011) and at follow-up (P < .0001). According to a re-evaluation of preoperative MRIs and comparison with IMVSs, linear tumor borders, and linear morphology along the internal auditory canal wall, but not the presence of a dural tail, were significantly more present in ICMs (P = .0035, P = .0004, P = .1963, respectively). These characteristics could have led to a correct preoperative diagnosis in 61% of our cases.

CONCLUSION

Contrariwise to IMVSs, the frequent preoperative anacusis and facial palsy demonstrate the more aggressive nature of ICMs, which also carry a higher risk of postoperative facial palsy and difficulty to preserve hearing. An attentive evaluation of imaging should ease diagnosis, and asymptomatic or stable ICMs should be enrolled in a wait-and-scan protocol.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E413-E419, 2021.

Therapy of Sporadic and NF2-Related Vestibular Schwannoma

Vestibular schwannoma (VS) is a benign primary brain tumor that occurs sporadic or as part of a genetic syndrome. The most common cause is the mutation of the NF2 tumor suppressor gene that is involved in the production of the protein merlin. Merlin plays a role in cell growth and cell adhesion. In patients with NF2, the VSs arise bilaterally and coincide with other brain tumors. In sporadic VS, the tumor is typically unilateral and does not coincide in combination with other tumors. MRI is the standard imaging technique and can be used to assess the size and aspect of the tumor as well as the progression of disease. The preferred management of large VS in both VS types is surgery with or without adjuvant radiation. The management for the medium- or small-sized VS includes wait and scan, radiotherapy and/or surgery. This choice depends on the preference of the patient and institutional protocols. The outcomes of surgical and radiotherapy treatments are improving due to progress in surgical equipment/approaches, advances in radiation delivery techniques and dose optimizations protocols. The main purpose of the management of VS is preserving function as long as possible in combination with tumor control.

Bifid Facial Nerve with Dual Origin Identified During Resection of Vestibular Schwannoma

Facial nerve identification and preservation is a critical step in the resection of vestibular schwannoma. The use of intraoperative neurostimulation to positively identify the facial nerve along its entire course is essential to prevent injury. To our knowledge, this is the first reported case of a bifid facial nerve with a dual origin at the brainstem, which we observed during resection of vestibular schwannoma via the translabyrinthine approach. Both roots were visualized to join as one facial nerve trunk outside the brainstem in the cisternal segment of the facial nerve, and both trunks demonstrated positive signal with neurostimulation. This case highlights an important anatomic variation and also the importance of correct identification of facial nerve anatomy during resection of vestibular schwannoma and other pathologies within the cerebellopontine angle.